ACTG 370 - This is a study of Indinavir Sulfate (IDV, Crixivan) combination therapy. Its purpose is to determine the safety, tolerability, immunologic and virologic effects of three treatment regimens IDV will be used in combination with ZDV (zidovudine, AZT), d4T (stavudine, Zerit), DLV (delavirdine, Rescriptor), and/or 3TC (lamivudine, Epivir). The study was developed as a "roll-over" study for subjects who participated in ACTG 306. The primary objectives of the study are to compare the proportion of subjects in the two ZDV-containing arms who have a plasma HIV RNA concentration below the limit of detection (defined as < 500 copies/ml) at both weeks 20 and 24, and to compare the safety and tolerability of the different treatment regimens.